Rubber sealing members, sponge sealing members, and felt sealing members have conventionally been employed as sealing members to seal ends of rotating shafts which are rotating bodies in devices that handle powder. Of these sealing members, rubber sealing members, being viscoelastic, have high coefficients of friction. For this reason, rubber sealing members have produced heat at high rotational speeds, abrasion has caused decrease in seal performance, and there have been problems in terms of longevity. Moreover, in accompaniment to production of heat due to friction, where the powder which is the material being sealed is a powder comprising resin as is the case with the toner in an electrophotographic apparatus, there has been the problem that the heat due to friction has caused the powder to soften and to adhere to the rotating shaft, causing the rotating apparatus of the electrophotographic apparatus to lock up. Furthermore, at seals comprising contact produced by sealing member surfaces, increase in torque has caused problems in terms of longevity of the rotating apparatus.
On the other hand, with sponge sealing members, because the sealing members have voids, it is common practice to use these while they are in a compressed state. However, because the sealing members have voids, powder which has entered the interior of the sealing member causes decrease in seal performance, and as is the case with rubber sealing members, there has been the problem that at high rotational speeds the heat due to friction causes the powdered resin which is the material being sealed to soften and to adhere to the rotating shaft, causing the rotating apparatus to lock up.
Moreover, with felt sealing members, because these employ felt which has been manufactured through compression of fibers, and because directionality of the fibers is irregular, it has been the case that once powder begins to enter the spaces between fibers within the sealing member, control of powder becomes impossible, and there has been occurrence of decrease in seal performance.
For these reasons, characteristics sought in a sealing member for powder in an apparatus or the like that handles powder include satisfactory seal characteristics, low force of friction, long life, low cost, and so forth.
There is therefore a sealing member for powder comprising woven pile fabric in which pile is napped from the surface of the base fabric, the fibers of the cut pile obtained as a result of cutting in such fashion as to cause the tips of the pile of this woven fabric to be at a uniform level being groomed so as to be in the rotational direction of the rotating body; and in addition, the spaces present at the base of this pile are blocked by crimped fibers which are included within this pile, reducing the spaces, as a result of which entry thereinto by powder is prevented (see, for example, Patent Reference No. 1).
Furthermore, a sealing member comprising sponge and felt has been proposed in which felt is arranged at the surface of a sponge or other such foam substrate, sealing being carried out by causing the surface of the felt to come in contact with the outer circumferential surface of a rotating body, or yarn comprising hollow fiber or porous hollow fiber is used as pile yarn to constitute a sealing member for a rotating body (see, for example, Patent Reference No. 2).
But because these sealing members are fundamentally planar sealing members, they must be bent in circular fashion if they are to be used at the rotating shaft of a rotating body. For this reason, because automatic insertion has been difficult, and a manual operation has been required, mechanization has been difficult to achieve.
The inventors of the present invention have therefore developed, in the context of a cylindrical seal member for preventing leakage of powder which may be employed as a shaft seal at a rotating shaft of a powder processor roller or the like which carries out processing using powder, a cylindrical seal member which, as a result of the fact that the diameter of the cylindrical seal member, which has a slit, shrinks in correspondence to the diameter of a hole for attachment of the cylindrical seal member so as to permit attachment thereto, makes it possible during installation for the diameter to shrink and after attachment for springback of the slit to cause enlargement, the fact that the central hole diameter formed by pile or fiber at the cylindrical seal member is capable of easily being enlarged to accommodate the diameter of the rotating shaft at the rotating body facilitating engagement with the rotating shaft, and also making automatic insertion during installation of the cylindrical seal member possible, and the fact that the cylindrical seal member is such that the outside diameter of the cylindrical seal member is capable of shrinkage as a result of the force of pressure acting on the outside circumference from the attachment hole making it possible to definitively stop leakage of powder from the rotating shaft (see, for example, Patent Reference No. 3).
However, as this cylindrical seal member is such that the slit which produces the springback is an inclined slit or a zigzag-shaped slit, because the tip of the cut portion produced by cutting in inclined or a zigzag fashion during manufacturing forms an acute angle, there are concerns with respect to safety during handling by workers. Furthermore, because the cylindrical seal member is such that the shape thereof is not rectangular, punching must be carried out in an operation that takes place prior to when this is made to assume a cylindrical shape during fabrication, and so there have been problems in that there is loss of material as a result of punching and in that manufacturing time cannot be shortened.